Process of making salts of anthraquinone sulfonic acids.



(5 acid referred to.

EDWARD G. GRIFFIN, 0F CLIFFSIDE, NEW JERSEY, ASSIGNOR TO THE BARRETTCOMPANY, A CORPORATION OF NEW JERSEY.

PROCESS OF MAKING SALTS OF ANTHRAQUINONE SULFONIG ACIDS.

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acids. While the process is applicable to.

either the a or the B mono-sulfonic acid derivative of anthraquinone,and also to analogous substances, I shall describe the processparticularly in connection with the Moreover, while the process may beutilized for the production of such salts of any one of the alkalimetals,

I shall, by way of example, describe my' process with relation to themanufacture of the sodium salt of anthraquinone (5 monosulfonic acid,commonly referred to as s1l ver salt. However, it is to be understood.

that, except as certain of the claims may specifically include suchlimitations, my invention is not to be limited or restricted to anyparticular one of the metals or of the mono-sulfonic acid derivatives ofanthraoxids or hydroxids previously employed, a

much cheaper material may be used with equal success and without anydiminution in the yield of the salt desired to be obtained.

Briefly stated, then, my process comprises the treatment of either the aor {5 anthraquinone mono-sulfonic acid with the alkali metal salt of anyof the usual mineral-acids. In preparing the sodium salt of the 5 acid,for example, I may use the sulfate (normal or acid), the chlorid, or anyother mineral acid salt of sodium,

The purpose in employing a mineral acid salt of one of the alkali metalsis that the anthraquinone monosulfonates of such met- Specific'ation ofLetters Patent.

Patented Mar. 26, T9 18.

Application filed March 22, 1917. Serial No. 156,747.

als are comparatively insoluble while the anthraquinone di-sulfonatesare comparatively soluble. Accordingly, by the addition of an alkalimetal salt of a mineral acid, the corresponding mono-sulfonate isprecipitated, thereby effecting its separation from any anthraquinonedi-sulfonic acids (usually the 2: 6 and.2:7 acids) present in thesolution to which the mineral acid alkali metal salt is added. Thispoint is of great practical importance since by the usual method ofpreparation, the anthraquinone mono-sulfonic acid is almost alwaysassociated with a substantial amount of anthraquinone di-sulfonic acids.By my method I am enabled to obtain the desired mono-sulfonatesubstantially free from anthraquinone di-sulfonic acids or their salts,and at the same time carry out this process in such a Way, as to effectsuch a separation of the two classes of acids that the di-acids may beobtained in a substantially uncontaminated form free from any mono-acidsor their salts, for any purpose for which the di-acids may be desired.

Whilean mineral acid salt of an alkali metal may e employed with successin my process, I prefer to use a sulfate, since by the use of such asulfate, inasmuch as the free acid present in the original acid solutionof the monoand di-acids is sulfuric acid, but one acid radical will bepresent in the solution, rendering the subsequent purification of thevarious products simple and feasible. Especially is this the case in thesubsequent recovery and purification of the di-acids in the filtrateobtained after filtering off the crystals of insoluble alkali metal andin addition as being one of the cheapest substances obtainable.

However, it is to be understood that other mineral acid salts of thedesired metal, Whether such salts are neutral, acid, or basic, may beemployed. Throughout the specification and claims wherever the phraseanthraquinone mono-sulfonic acid appears I mean to designate both the aand (5 acids a sufficient amount of the alkali metal salt of or mixturesof such acids. any mineral acid to supply enough of the In practising myprocess, I treat any demetal radical toproduce the desired salt of siredquantity of either the a or the (3 anthrathe anthraquinone mono-sulfonicacid acquinone mono -sulfonic acid,in solution, with cording to thefollowing reaction:

where M stands for any alkali metal and X. thraquinone is washed withwater and the for any mineral acid radical, the (5 acid bewash water isadded to the first filtrate. The ing indicated by way of example. Therefiltrate consists principally of anthraquinone action is entirelyanalogous in the case where mono-sulfonic acid, together with asubstanthe 0: acid is used. tial amount of anthraquinone di-sulfonic Itis immaterial for the purposes ofmy acids all in acid solution, the freeacid being present invention, how the solutionof either sulfuric acid.the a or the [5 acid is obtained. A solution of However obtained, thesolution of either the 5 acid may be obtained as follows: Any the or or(5 mono-sulfonic acid is treated with desired amount of anthraquinone isheated either a normal or acid mineral acid salt with an excess offuming sulfuric acid or of the desired alkali metal. 0f such salts,oleum at about 170 for about 10 hours. I prefer to use the sulfates, forthe reason The hot sulfonated mixture is poured slowly already setforth. Using normal sodium with stirring into several times its volumesulfate and the 6 acid, for example, the'folof cold water and theresulting mass is lowing reaction takes place: boiled and filtered. Theunsulfonated an- The sodium" sulfate may be added either comprises thestep of treating such acid in the form of crystals (Glaubers salt), inwith an alkali metal salt of sulfuric acid, the form of an anhydrouspowder, or as an substantially as described. aqueous solution. Enough ofthe sulfate is 3. The process of forming the sodium salts added toneutralize the 6 acid present. Afof anthra-quinone mono-sulfonic acidwhich ter' the action is complete, the mixture is comprises the step oftreating such acid with concentrated, and after cooling, the thick thesodium salt of such a mineral acid as crystalline mass is filtered andwashed sevwill form a precipitate, and separating the eral times with a10% sodium sulfate soluprecipitate from the liquid portion, substantion.The di-sulfonic acid compounds, betially as described. ing comparativelyvery soluble, do not crys 4. The process of forming the sodium tallizeout of the solution with the anthrasalts of, anthraquinone mono-sulfonicacid quinone mono-sulfonic acid salt, and the latwhich comprises thestep of treating such ter is accordingly obtained in a substantiallyacid with sodium sulfate, substantially as pure condition. In a similarmanner the described. v sodium or other alkali salts of either the oz 5.The processof formingthe sodiumsalt of or [5 anthraquinone mono-sulfonicacid may anthraquinone {5 mono-sulfonic acid which be obtained bytreatment of either the a or comprises the step of treating such acidwith (5 acid, as desired, with a mineral acid salt, the sodium salt of amineral acid, subeither normal or acid, of the desired metal. stantiallyas described.

What I claim is: 6. The process of forming the sodium salt 1. Theprocess of forming salts of anof anthraquinone [5 mono-sulfonie acidthraquinone mono-sulfonic acid which comwhich comprises the step oftreatin such prises the step of treating such acid with acid with sodiumsulfate, substantiallly as an alkali metal salt .of sulfuric acid,subdescribed. stantially as described. 7. The process of efiectingaseparation 2. The process of formin salts of anand recovery ofanthraquinone mono-sulfo-- thraqumone {l mono-sulfomc acid which mo anddl-sulfonic acids in a solut on containing such acids, which comprisesthe steps of adding a mineral acid salt of an alkali metal to suchsolution and filtering off the comparatively insoluble alkali metalanthraquinone mono-sulfonate formed, whereby the anthraquinonedi-sulfonic acids are left in the filtrate substantially free fromanthraquinone m0no-sulfonic acid and its salts, substantially asdescribed.

8. The process of effecting a separation and recovery of anthraquinonemono-sulfonic and di-sulfonic acids in a solution containing such acids,which comprises the steps of adding a sulfate of an alkali metal to suchsolution and filtering off the comparatively insoluble alkali metalanthraquinone mono-sulfonate f0rmed,Whereby the anthraquinonedi-sulfonic acids are left in the filtrate substantially free fromanthraquinone mono-sulfonic acid and its salts, substantially asdescribed.

i 9. The process of effecting a separation and recovery of anthraquinonemono-sulfonic and di-sulfonic acids in a solution containing such acids,which comprises the steps of adding sodium sulfate to such solution, andfiltering oil the comparatively insoluble sodium anthraquinonemono-sulfonate formed whereby the anthraquinone di-sulfonic acids areleft in the filtrate substantially free from anthraquinone mono-sulfonicacid and its salts, substantially as described.

10. The process of effecting a separation and recovery of anthraquinonemono-sulfonic and di-sulfonic acids in a solution containing such acids,which comprises the steps of adding sodium sulfate to such solution,filtering ofl the comparatively insoluble sodium anthraquinonemono-sulfonate formed, whereby the anthraquinone di-sulfonic acids areleft in the filtrate substantially free from anthraquinone monosulfonicacid and its salts, and recovering the di-sulfonic acids in acomparatively pure form, substantially as described.

In testimony whereof I affix my signature.

EDWARD G. GRIFFIN.

